Two-Stage Turbo Puts on the Pressure

Regulated 2-stage turbocharging from BorgWarner Turbo & Emissions Systems is set to take the U.S. market by storm in the 6.4-liter V8 diesel engine from International and Ford.
The North American Diesel engine pickup truck market continues to be driven by more stringent emission requirements and increases in power and torque. These requirements compel manufacturers to find new technologies to meet these challenges. International Truck and Engine Corporation as well as Ford Motor Company have overcome this challenge with the all new PowerStroke 6.4-liter V8 diesel engine. A key technology enabler in achieving these goals is the BorgWarner Turbo & Emissions System’s regulated 2-stage turbocharger (R2S). This is the most recent highlight in the development cooperation between BorgWarner Turbo & Emissions Systems, International and Ford. “Three innovative companies have successfully combined their expertise in close cooperation to deliver this exceptional new product. The result is a dual turbocharged V8 engine with technology that will play a major role in the further spread of the diesel engine in the U.S. market,” said Roger J. Wood, Vice President of BorgWarner Inc. and President and General Manager of BorgWarner Turbo & Emissions Systems. R2S technology provides the end user with a product that meets the new stringent emission requirements without compromising increased horsepower and torque. The powerful engine will be installed under the name PowerStroke in the F series of heavy-duty pickup trucks, the F250, F350, F450, and F550 from Ford Motor Company, as well as in light trucks from International, where it goes by the name of MaxForce7. With the launch of the PowerStroke 6.4-liter V8 diesel engine, Ford, the U.S. market leader in the heavy-duty pickup segment, is setting a clear signal for the wide-scale introduction of R2S technology in this vehicle category.
Two premieres under one hood
The 6.4-liter turbodiesel engine gives the American heavy-duty pickup segment the first opportunity to take advantage of the numerous benefits of regulated two-stage turbocharging. This turbocharging system consists of two differently sized turbochargers arranged in series. The smaller high-pressure turbocharger responds spontaneously and harmoniously at low engine speeds while the larger low-pressure unit is responsible for providing boost at higher engine speeds. In order to make the infinitely variable adaptation of the turbine side to the compressor side even more efficient for every engine operating state, a turbocharger with variable turbine geometry (VTG) is used in the high-pressure stage – a world premiere in combination with the R2S system. Fast and precise adjustment of the VTG guide vanes is ensured by an electric actuator motor, which BorgWarner Turbo & Emissions Systems has specially developed for this turbocharger. The V8 engine features excellent acceleration, high torque and an impressive power density. The compact dimensions made it possible to accommodate the entire R2S assembly in a space-saving manner in the V of the eight-cylinder diesel.
The innovations featured in this fuel-efficient diesel engine are also beneficial to the environment. In order to further reduce NOx emissions, exhaust gas recirculation (EGR) also takes place at full load. The two-stage system is particularly good at providing the high boost pressures required over a wide operating range. The modern 6.4-liter engine easily complies with even the strictest U.S. emissions standards.
Growth due to turbocharging
In its successful cooperation with International Truck and Engine Corporation and Ford Motor Company, BorgWarner Turbo & Emissions Systems has once again demonstrated its technological leadership in the field of regulated two-stage turbocharging. The benefits of this innovative turbocharging system are now available in every segment of the market — from passenger car engines right up to large power units for trucks. The production figures planned by Ford in the heavy-duty pickup segment in particular make this the biggest R2S project yet for BorgWarner Turbo & Emissions Systems. To meet this demand, the company has designed, built and put into operation state-of-the-art production lines for the manufacture and assembly of these turbocharger systems at its turbocharger plant in Asheville, North Carolina, U.S.A.
Cooperation between BorgWarner Turbo & Emissions Systems and International began several years ago when its started supplying VTG turbochargers for the 6-cylinder inline commercial vehicle engine, followed by the introduction of R2S technology in the 4.5-liter V6.